Vane pump with brittle vanes and rough finished housing surface

Abstract

A vane pump in which an engaging portion in engagement with vanes to restrain the protrusion of the vanes to a given amount is provided on the inner surface of an end wall of a housing, the vanes being made of a material having a relatively high brittleness, the housing having an inner peripheral surface finished into a rough surface so as to restrain the sliding resistance of the vanes resulting from rotation thereof.

What is claimed is: 
     
       1. A method of operating a vane pump of the type having a housing with a rotor chamber having an inner peripheral surface, a rotor rotatably mounted in the rotor chamber and having an axis of rotatation which is eccentric relative to the axis of the inner peripheral surface of the rotor chamber, the rotor having a plurality of generally radially disposed vane slots, and a plurality of vanes slidable mounted in the vane slots and operable to define variable volume chambers for effecting a pumping action as the rotor rotates and the vanes move generally radially in and out of the vane slots, the method of operation comprising the steps of limiting the radial outward movement of said vanes from said vane slots to provide a minimal near-zero clearance between the outer radial ends of said vanes and the inner peripheral surface of said rotor chamber, providing a roughened surface on said inner peripheral surface of said rotor chamber, operating said vane pump with said minimal near-zero clearance between the outer radial ends of said vanes and the inner peripheral roughened surface of said rotor chamber, continuing to operate said vane pump over a prolonged period of time to the extent that wear occurs and that as a result of said wear, said minimal near-zero clearance between the outer radial ends of said vanes and the inner peripheral roughened surface of said rotor chamber is reduced to zero, and immediately abrading said outer radial ends of said vanes by contact with said roughened surface such that said minimal near-zero clearance is reestablished between the outer radial ends of said vanes and the inner peripheral surface of said rotor chamber. 
     
     
       2. A vane pump comprising a housing means having a rotor chamber, said rotor chamber having an inner peripheral surface, a rotor means rotatably mounted in said rotor chamber, said inner peripheral surface having an axis which is eccentric relative to the axis of rotation of said rotor means, said rotor means having a plurality of generally radially disposed vane slots, a plurality of vane means slidably mounted in said vane slots and operable to define variable volume chambers for effecting a pumping action as said rotor means rotates and said vane means moves generally radially in and out of said vane slots, vane-limiting means in said housing means operable to engage said vane means to limit the extent of the outer radial movement of said vane means out of said slots to thereby provide a clearance between the outer radial ends of said vane means and said inner peripheral surface of said rotor chamber, said vane means being made of a brittle material, said housing means being made of a metal material, said inner peripheral surface of said rotor chamber being a roughened metal surface formed in the metal material of said housing means such that when wear occurs in said vane-limiting means after prolonged operation of the vane pump to the extent that said vane means extend further radially outwardly of said slots to the extent of said clearance as a result of said wear to contact said roughened metal surface, said brittle vane means are immediately abraded by said roughened metal surface to thereby establish a minimal near-zero operating clearance between said brittle vane means and said roughened metal surface. 
     
     
       3. A vane pump according to claim 2, wherein said roughened surface has a depth of at least 10 μ. 
     
     
       4. A vane pump according to claim 2, wherein said vane means are made of a carbon material. 
     
     
       5. A vane pump according to claim 2, wherein said housing means is made of aluminum.